jQuery methods html('') vs empty()

[madeinua]

I found that in a many places in WP uses .html('') instead of .empty()

There is a few advantages to use the second one:

1. $.empty() works faster
2. $.html('') creates memory leak
3. $.empty() is more readable

Confirmation of these words you can find on the internet (e.g. stackoverflow).

Thanks!

[SergeyBiryukov]

According to ​jQuery documentation, empty() also removes event handlers from child elements, so we should verify that doesn't affect any of the instances here.

[madeinua]

true, in this cases you can use .detach()

[nacin]

In order to touch this we'd have to ensure there are no side effects for any one of these changes.

[OriginalEXE]

Removing events is only 'dangerous' if removed elements are going to be returned to the dom.

From my inspection, this does not happen anywhere. The only place where object is returned (and where events could potentially break) when .html('') is used is in wp-ajax-response.js, so just to be sure, i used detach() there instead.

[helen]

We may not be set up to handle this right now, but just a note for now/the future that it would be nice if this was testable in some way, particularly in terms of performance.

[adamsilverstein]

Replying to helen:

We may not be set up to handle this right now, but just a note for now/the future that it would be nice if this was testable in some way, particularly in terms of performance.

Here is some jsPerf data comparing speed for empty(), html() and native .innerHTML =

​http://jsperf.com/empty-vs-html/2

[wonderboymusic]

I just looked at every line these touch, they are all arbitrary uses of .html('')

[wonderboymusic]

In 31690:

Replace flagrant instances of .html('') with .empty().

Props OriginalEXE, SergeyBiryukov.
Fixes #27034.